1 Pluto loses status as a planet on Fri Sep 10, 2010 10:55 pm
About 2,500 astronomers and experts who meet today in Prague the Czech capital for the International Astronomical Union’s (IAU) general assembly have voted to strip Pluto of its status as a planet.
Pluto had been considered a planet since its discovery in 1930 by the American Clyde Tombaugh. So to now have pluto effectively airbrushed out of school and university textbooks is something that I think is quite unreal as there always used to been nine planets!
The astronomers at the IAU meeting voted by raising their yellow ballot papers for a count. And then after counting the votes the IAU resolution announced “The eight planets are Mercury, Earth, Venus, Mars, Jupiter, Saturn, Uranus and Neptune”
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Read more about this news over at the BBC News Website!
Update: The Resolution is as follows from the IAU Website:
The IAU therefore resolves that “planets” and other bodies in our Solar System be defined into three distinct categories in the following way:
(1) A “planet”1 is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.
(2) A “dwarf planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape2 , (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
(3) All other objects3 except satellites orbiting the Sun shall be referred to collectively as “Small Solar-System Bodies”.
1The eight planets are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
2An IAU process will be established to assign borderline objects into either dwarf planet and other categories.
3These currently include most of the Solar System asteroids, most Trans-Neptunian Objects (TNOs), comets, and other small bodies.]